Reduce sql queries for groupname tests. (STUD-1039)

Conflicts:
	cms/djangoapps/auth/authz.py

cms/djangoapps/auth/authz.py

@@ -63,7 +63,7 @@ def get_all_course_role_groupnames(location, role, use_filter=True):
     # filter to the ones which exist
     default = groupnames[0]
     if use_filter:
-        groupnames = [group for group in groupnames if Group.objects.filter(name=group).exists()]
+        groupnames = [group.name for group in Group.objects.filter(name__in=groupnames)]
     return groupnames, default
 
 
@@ -203,12 +203,9 @@ def remove_user_from_course_group(caller, user, location, role):
 
     # see if the user is actually in that role, if not then we don't have to do anything
     groupnames, _ = get_all_course_role_groupnames(location, role)
-    for groupname in groupnames:
-        groups = user.groups.filter(name=groupname)
-        if groups:
-            # will only be one with that name
-            user.groups.remove(groups[0])
-            user.save()
+    for group in user.groups.filter(name__in=groupnames):
+        user.groups.remove(group)
+    user.save()
 
 
 def remove_user_from_creator_group(caller, user):
@@ -243,7 +240,7 @@ def is_user_in_course_group_role(user, location, role, check_staff=True):
         if check_staff and user.is_staff:
             return True
         groupnames, _ = get_all_course_role_groupnames(location, role)
-        return any(user.groups.filter(name=groupname).exists() for groupname in groupnames)
+        return user.groups.filter(name__in=groupnames).exists()
 
     return False
 
@@ -266,7 +263,7 @@ def is_user_in_creator_group(user):
 
     # Feature flag for using the creator group setting. Will be removed once the feature is complete.
     if settings.MITX_FEATURES.get('ENABLE_CREATOR_GROUP', False):
-        return user.groups.filter(name=COURSE_CREATOR_GROUP_NAME).count() > 0
+        return user.groups.filter(name=COURSE_CREATOR_GROUP_NAME).exists()
 
     return True
 

lms/djangoapps/courseware/roles.py

@@ -4,7 +4,6 @@
 """
 
 from abc import ABCMeta, abstractmethod
-from functools import partial
 
 from django.contrib.auth.models import User, Group